The invention relates to an injection device.
An injection device using suction has been proposed in U.S. Pat. No. 4,114,619. The proposed device has an open cavity with an injection needle projecting from the bottom of the cavity. The open cavity is applied to the skin. When the opening of the cavity is placed correctly sensors activate a suction piston which creates a vacuum in the cavity. This vacuum draws the skin towards the bottom of the cavity and then causes penetration by the injection needle projecting from the bottom of the cavity. A second detector, consisting of a pressure transducer, activates the piston of the injection syringe.
The purpose of the device of U.S. Pat. No. 4,114,619 is to achieve complete automation of the injection process once the opening of the cavity is correctly placed in contact with this tissue. In consequence the design of the device for executing this automatic process is relatively complex.
It is an object of the present invention to provide an injection device of simplified design.
It is a further object of the invention to provide an injection device that can be simply manufactured, at low cost.
It is a further object of the invention to provide an injection device that is easily portable.
The invention exploits the concept which consists of making the cutaneous tissue penetrate inside the needle rather than the inverse, as in traditional injection syringes. The invention provides a device of the simplest possible design so that it can be manufactured at low cost and be simple and easy to use. This result is achieved by creating in the injection area, as in the device mentioned above, a vacuum by the use of an open cavity whose opening is applied to the skin so as to draw it up against the injection needle projecting from the bottom of the cavity.
The invention provides an injection device having an open cavity whose opening is delimited by an annular rim intended for application to the skin of a subject under treatment, an injection needle projecting from the bottom of the cavity, its forward end being set back in respect of the annular rim, a first, leakproof compartment delimited by a first mobile barrier, means for displacing the first mobile barrier so as to vary the volume of the first compartment, at least one communicating passage between the first leakproof compartment and the cavity, a second leakproof compartment for a product to be injected, delimited by a second mobile barrier, a second means for displacing the said second section of a mobile barrier so as to vary the volume of the second leakproof compartment, and an opening to enable the second leakproof compartment to communicate with the said injection needle.
In the case of self-injection the person performing the injection does not himself have to make the needle penetrate the cutaneous tissue, which is a notable improvement from the psychological standpoint. The drawing up of the skin reduces the perception of pain caused by the penetration of the needle. The depth of needle penetration is perfectly regulated by the length to which the needle projects from the bottom of the cavity, a safety feature likely to be reassuring, particularly to the person who must perform self-injection.